How did you lose Costa Rican nationality, and when?
Since 6 June 1995 Article 16 of the Constitution says being Costa Rican cannot be lost or renounced, so the date of any recorded loss matters most. Before then it was lost by taking another nationality, or for naturalised Costa Ricans also by six years of continuous absence. If you do not know the date, the Registro Civil can search your entry for any note of a loss.